1. Field of the Invention
The present invention relates to a transmission apparatus for transmitting power. More specifically, the present invention relates to a transmission apparatus for transmitting power from a motor for driving an airport ground support tractor.
2. Background Information
In the operation of an airport, passenger luggage and the like must be transported from the departure terminal to the aircraft to be loaded. Similarly, at the arrival terminal, planes must be unloaded and the luggage therefrom must be efficiently transported to the arrival terminal.
Accordingly, most terminals are provided with a fleet of tractors for hauling a train of luggage trailers between the planes and the terminals.
However, when the luggage trailers are loaded, a relatively low gear ratio is required in order to haul the heavy load. When the luggage trailers have been unloaded, pulling the unloaded trailers can be accomplished using a relatively high gear ratio so that the tractor can rapidly return for reloading.
Although manual two speed gearbox arrangements have been provided, such manual two speed gearboxes are subject to rapid wear. Also, such two speed gearboxes must be provided with a reverse gear ratio for permitting maneuvering of the tractor.
The present invention overcomes the rapid wear problems associated with the prior art two speed manual gearbox arrangements while avoiding the excessive cost involved in the provision of a conventional fully automatic gear transmission.
Accordingly, the present invention provides a unique combination of a simplified automatic transmission for providing forward and reverse movement while including a semi manual two speed gearbox having a low gear ratio for pulling heavy loads and a relatively high gear ratio for a rapid return to a luggage loading station.
Therefore, the primary feature of the present invention is the provision of a transmission apparatus that overcomes the problems associated with the prior art transmission arrangements and which makes a significant contribution to the tractor power transmission art.
Another feature of the present invention is the provision of a transmission apparatus that reduces the rapid wear problem associated with known manual gearboxes while avoiding the excessive cost of providing a fully automatic conventional transmission.
Other features and advantages of the present invention will be readily apparent to those skilled in the art by a consideration of the detailed description of a preferred embodiment of the present invention contained herein.